Farmers colonizing the plains of the Indus and Saraswati in the early 3rd millennium BC entered a land of both opportunities and dangers. This vast alluvial area provided fertile agricultural land capable of yielding two harvests a year.
But this abundance had its price. Rivers could change their course, leaving fields and dependent settlements suddenly stranded in hostile desert. They could also rise suddenly and dramatically, flooding settlements - and Indus farmers rapidly learnt to build massive baked brick flood defences around their towns.
The wildlife of the jungle or scrub, such as tiger, rhinoceros and boar, provided excitement and danger for farmers hunting deer and other game - but far more menacing was another local inhabitant - the malarial mosquito.
Fish in the rivers, fish and shellfish in the sea added to the wealth in natural foods, and the colonizing farmers brought crops and domestic animals. Wheat, barley and pulses like sesamum, peas and mustard, as well as cotton for cloth, were grown in fields just like those cultivated today, as we know from the discovery of a criss-cross ploughed field at Kalibangan.
Ploughs would have been drawn by bullocks, which were also harnessed to carts. Dew-lapped humped zebu cattle were the chief domestic animals; buffaloes, sheep, goats and chickens were also kept.
Many Indus inhabitants were pastoralists who migrated between seasonal pastures. It was probably they who maintained the close links that existed between the settlements of the Indus civilization, using their cattle to carry goods, as do modern pastoralists in the region.
During the later Indus period, new crops came into cultivation: locally domesticated rice in Gujurat and the east, and millets introduced from Africa via Arabia. Unlike wheat and barley, still today the staples of the Indus plains, rice and millets are tropical crops whose cultivation opened new horizons to Indus farmers - the Ganges valley and peninsular India, regions where prosperous farming communities developed after the Indus civilization declined.